.flow-wave {
    padding: 5px 0;
}
.flow-wave:hover,
.flow-wave:focus {
    background: radial-gradient(circle at 10px -7px, transparent 8px, currentColor 8px, currentColor 9px, transparent 9px) repeat-x,
        radial-gradient(circle at 10px 27px, transparent 8px, currentColor 8px, currentColor 9px, transparent 9px) repeat-x;
    background-size: 20px 20px;
    background-position: -10px calc(100% + 16px), 0 calc(100% - 4px);
    animation: waveFlow 1s infinite linear;
}
@keyframes waveFlow {
    from { background-position-x: -10px, 0; }
    to { background-position-x: -30px, -20px; }
}